Low voltage discharge tube



March 22, 1966 c. s. REIS LOW VOLTAGE DISCHARGE TUBE Filed Nov. 1, 1965FIQ' i SIGNAL SOURCE INVENTOR CHARLES s, REIS BY K ATTORNEY UnitedStates Patent 3,242,377 LOW VOLTAGE DISCHARGE TUBE Charles S. Reis,Mountain View, Calif., assignor to Hewlett-Packard Company, Palo Alto,Calif., a corporation of California Filed Nov. 1, 1963, Ser. No. 320,8053 Claims. (Ci. SIS-84.6)

This invention relates to an improved gas discharge tube which can beturned on and off at high repetition rates using low voltage controlsignals.

It is an object of the present invention to provide a gas discharge tubewhich can be triggered from one conduction state to another at extremelyhigh repetition rates.

It is another object of the present invention to provide a dischargetube which has no ionization time delay during transitions betweenconduction states.

These and other objects of the present invention will be apparent from areading of this specification and an inspection of the accompanyingdrawing in which FIG- URES 1 and 2 are, respectively a perspective viewof the discharge tube of the present invention and a side sectional viewof the electrode structure of the discharge tube of FIGURE 1.

The transition times between conduction states of a gas discharge tubeare greatly reduced in the instant invention by maintaining continuousionization and by switching the electrodes between which the ionizationis sustained. A pair of semicircular cathode electrodes 9 and 11 areseparated by an anode electrode 13 having an aperture 15 therein aboutin line with the surfaces of electrodes 9 and 11. An auxiliary electrode17 is attached to electrode 11 and passes through the aperture 15,terminating near the edge 19 of electrode 9. These electrodes are sealedwithin envelope 21 which is filled with neon gas 23 at a pressure of 35mm. of mercury. The electrodes 9 and 11 are made of zirconium-nickelalloy and are treated on the upper surfaces thereof with anelectron-emissive coating as described in US. patent applicationentitled Glow Discharge Tubes filed by Charles S. Reis on October 14,1963. The lower surfaces of electrodes 9 and 11 are treated with ananti-emissive coating consisting of A1 0 or metallic aluminum powder.This aids in confining the glow of ionized gas to the upper surfaces ofelectrodes 9 and 11.

In operation, cathode electrode 9 is made sufiiciently negative withrespect to anode electrode 13 to initiate conduction in the rightportion of the tube. The gas 23 remains ionized in the region ofelectrodes 9 and 13 as long as the dilference of potential between theseelectrodes is maintained above the sustaining voltage. This region ofionization is shifted to the other side of electrode 13 by theapplication to the electrode 11 of a low voltage, say volts, which isnegative with respect to electrode 9. The region of ionized gas on theright side of electrode 13 near aperture 15 is influenced by theelectric field between electrode 13 and the auxiliary electrode 17 whichis connected to electrode 11. The glow discharge is established betweenelectrodes 11 and 13 and is extinguished between electrodes 9 and 13.This is because the greater negative voltage on electrode 11 has theapparent effect of lowering the work function of the material ofelectrode 11 below that of electrode 9. If

the voltage on electrode 11 is now made less negative 6 than the voltageon electrode 9, the glow discharge is shifted from the left portion tothe right portion of the tube with glow discharge being maintainedcontinuously in the region about aperture 15 and auxiliary electrode 17.Ionization time is thus eliminated. Also, since only the electrodehaving the effectively lower work function sustains glow discharge, thetube can be operated as a two-state logic or counting device whichcannot be locked out or double triggered. One tube produced according tothe present invention was successfully operated between the twooperating states at a rate of 500 kilocycles per second using a typicalexternal circuit such as the circuit shown generally as 25. Opticalmasking of one portion of the tube from the other portion enables thetube to be used as a logic device which provides an indication of itsown operating state. A ring counter having a plurality of stablecondition and providing indications of its operating states may also beproduced according to the present invention by arranging a plurality ofcircular segments within the tube with an anode disposed between eachsegment. Each anode has an aperture therein in line with the surface ofthe segments.

An auxiliary electrode on each segment passes through the aperture of anadjacent anode either from the clockwise or counter-clockwise adjacentsegment.

I claim:

1. A gas discharge tube comprising:

an envelope having gas therein;

a pair of cathode electrodes spaced away from each other sealed withinsaid envelope;

an anode electrode within said envelope disposed be tween said pair ofcathode electrodes;

said anode electrode having an aperture therein; and

an auxiliary electrode connected to one of said pair of cathodeelectrodes;

said auxiliary electrode passing through said aperture and terminatingnear the other of said pair of cathode electrodes.

2. A gas discharge tube as in claim 1 wherein said gas neon.

3. In combination, a gas discharge tube including an envelope havingneon gas therein;

a pair of electrodes spaced away from each other sealed within saidenvelope;

a third electrode within said envelope disposed between said pair ofelectrodes;

said third electrode having an aperture therein;

an auxiliary electrode connected to one of said pair of electrodes;

said auxiliary electrode passing through said aperture and terminatingnear the other of said pair of electrodes;

means producing between said third electrode and said one electrode apotential difference higher than the ionization sustaining potential forsaid gas; and

means connected to the other of said pair of electrodes for applyingthereto a potential of one polarity which is higher than the potentialon said one electrode.

References Cited by the Examiner UNITED STATES PATENTS 6/1957 Geisler3l584.6 X 8/1959 Crowther 3l3-210 X

1. A GAS DISCHARGE TUBE COMPRISING: AN ENVELOPE HAVING GAS THEREIN; APAIR OF CATHODE ELECTRODES SPACED AWAY FROM EACH OTHER SEALED WITHINSAID ENVELOPE; AN ANODE ELECTRODE WITHIN SAID ENVELOPE DISPOSED BETWEENSAID PAIR OF CATHODE ELECTRODES; SAID ANODE ELECTRODE HAVING AN APERTURETHEREIN; AND